The present invention relates to door locking devices, and particularly to the type including one or more locking bolts which are movable to their locking position by a key-operated cylinder.
Many different constructions of door-locking devices of the foregoing type have been developed and are commercially available. In the more popular constructions, after the door has been closed, the user must perform additional manipulations (e.g., insert the key and rotate the cylinder) in order to securely lock the door in its closed condition. While doors frequently have spring-actuated latches which are actuated by merely closing the door, these latches can usually be opened by an authorized person without too much difficulty and therefore do not provide secure protection when the door is closed, the secure protection being usually provided only by the additional manipulations on the part of the user, such as the insertion and rotation of his key and/or the rotation of the door handle. As a result, a user frequently merely closes the door, and thereby leaves the door protected against unauthorized opening only by the spring-latch which, as mentioned above, does not provide secure protection.